Assuming that the NTL is USB, it can be connected directly to the PC, but there will be a limit on the cable length supported - maybe 5 metres - does anyone know? But you can get repeaters.

If you are going to use a wireless router, it needs to incorporate an ADSL modem (to replace the NTL modem). Does the one that you have bought have a modem. You (almost certainly) won't be able to connect the NTL modem (assuming USB) to a wireless router as the wireless router will be ethernet, not USB.

So best if you tell us:What type of NTL modem (USB or ethernet)What type of wireless router (with / without ADSL modem)Distance a cable run from modem point to PC would need to be.

My NTL cable box to TV is upstairs (I have Satellite on my main TV) My computer is downstairs and the NTL engineer just fitted another cable connection from the main incoming cable through an outside wall to within 6ft of my computer and connected the modem up for me.

For wireless connection (as DieSse) says. Think of the Router as a "sender" so you would need a "receiver" fitted in your PC.